The centenary of the Great Kanto earthquake brings angst, and lessons for the world. From a report:

Every year on September 1st, Japan’s ministers trek by foot to the prime minister’s office to take part in a crisis simulation. Across the country, local officials and schoolchildren drill for disasters. The date marks the Great Kanto earthquake, a 7.9-magnitude tremor that struck near the capital back in 1923. The ensuing disaster killed at least 105,000 people, including around 70,000 in Tokyo itself, destroyed 370,000 homes and changed the course of Japanese history.

This year’s centenary of the disaster has occasioned much commemoration — and angst. What will happen when the next Big One hits? Seismologists cannot predict earthquakes, but their statistical models, which are based on past patterns, can estimate the likelihood of one. The city government’s experts reckon there is a 70% chance of a magnitude 7 or higher quake hitting the capital within the next 30 years. Far fewer people will probably die than during the disaster in 1923, thanks to better technology and planning: the worst case foresees some 6,000 deaths in the city. But millions of lives will be upended.

Another, similarly likely scenario could be much worse. A Nankai Trough earthquake, envisaged south of Kansai, Japan’s industrial heartland, could trigger a tsunami; as many as 323,000 might be killed, according to an official estimate. Japan’s approach to the risks of such catastrophes offers insights for a warming world facing more frequent disasters. Quakes of this size could “challenge the survival of Japan as a state” and send economic shock waves around the globe, says Fukuwa Nobuo of Nagoya University. After the next Tokyo quake, recovering basic city functions could take weeks and rebuilding the capital could take years; direct damage alone could run to as much as $75bn. One piece of research estimates that gdp would dip by 11% following a Nankai earthquake.


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